dextromethorphan and Hypertension

The combination of low rather than high dose of dextromethorphan (DXM) with amlodipine (AM) could improve blood pressure (BP) reduction in hypertensive animals. The study aimed to evaluate the feasibility of different doses of DXM combined with standard AM treatment in clinical hypertension.This was a prospective, 14-week, dose-escalation, multicenter study. After 2-week run-in period with AM 5 mg/day, hypertensive patients who got the BP goal of 140/90 mmHg kept receiving AM monotherapy for another 12 weeks. The nonresponders, while kept on AM 5 mg/day, received additional DXM treatment for 3 sequential dose-titrated periods with initially 2.5 mg/day, followed by 7.5 mg/day, and finally 30 mg/day. Each period was for 4 weeks. The patients at BP goal after each treatment period were defined as the responders and kept on the same combination till the end of the study. The responder rate of each treatment period was recorded. The changes of BP and serum antioxidant/endothelial markers between week 14 and week 2 were evaluated.Of the 103 patients initially enrolled, 89 entered the treatment period. In the 78 patients completing the study, 31 (40%) at BP goal after 2-week AM run-in kept on AM monotherapy (DXM0). The addition of 2.5 (DXM2.5) and 7.5 mg/day (DXM7.5) of DXM enabled BP goal achievement in 22 (47%) nonresponders to AM monotherapy including 16 (29%) with DXM2.5 and 6 (18%) with DXM7.5. Only 4 patients (16%) reached BP goal with the combination of DXM 30 mg/day (DXM30). Overall, 73% of the 78 patients reached BP goal at the end of the 14-week study. Mean systolic BP was reduced by 7.9% ± 7.0% with DXM2.5 (P < 0.001) and by 5.4% ± 2.4% with DXM7.5 (P = 0.003) respectively at week 14 from that at week 2, which was unchanged in either DXM0 or DXM30 group. Besides, the effects of combination treatment were particularly significant in the patients with impaired endothelial function suggested by reduced serum NOx level at baseline.Accordingly, the combination with low dose of DXM was feasible to improve BP control in patients who failed to achieve the BP goal by standard AM monotherapy. The benefit effects might be significant especially in patients with impaired endothelial function.

Topics: Amlodipine; Antihypertensive Agents; Dextromethorphan; Drug Therapy, Combination; Female; Humans; Hypertension; Male; Middle Aged; Prospective Studies; Single-Blind Method

Vascular oxidative stress may be increased with age and aggravate endothelial dysfunction and vascular injury in hypertension. This study aimed to investigate the effects of dextromethorphan (DM), a NADPH oxidase inhibitor, either alone or in combination treatment, on blood pressure (BP) and vascular protection in aged spontaneous hypertensive rats (SHRs).. Eighteen-week-old WKY rats and SHRs were housed for 2 weeks. SHRs were randomly assigned to one of the 12 groups: untreated; DM monotherapy with 1, 5 or 25 mg/kg/day; amlodipine (AM, a calcium channel blocker) monotherapy with 1 or 5 mg/kg/day; and combination therapy of DM 1, 5 or 25 mg/kg/day with AM 1 or 5 mg/kg/day individually for 4 weeks. The in vitro effects of DM were also examined. In SHRs, AM monotherapy dose-dependently reduced arterial systolic BP. DM in various doses significantly and similarly reduced arterial systolic BP. Combination of DM with AM gave additive effects on BP reduction. DM, either alone or in combination with AM, improved aortic endothelial function indicated by ex vivo acetylcholine-induced relaxation. The combination of low-dose DM with AM gave most significant inhibition on aortic wall thickness in SHRs. Plasma total antioxidant status was significantly increased by all the therapies except for the combination of high-dose DM with high-dose AM. Serum nitrite and nitrate level was significantly reduced by AM but not by DM or the combination of DM with AM. Furthermore, in vitro treatment with DM reduced angiotensin II-induced reactive oxygen species and NADPH oxidase activation in human aortic endothelial cells.. Treatment of DM reduced BP and enhanced vascular protection probably by inhibiting vascular NADPH oxidase in aged hypertensive animals with or without AM treatment. It provides the potential rationale to a novel combination treatment with low-dose DM and AM in clinical hypertension.

Topics: Angiotensin II; Animals; Blood Pressure; Cell Line; Dextromethorphan; Heart Rate; Humans; Hypertension; Male; NADPH Oxidases; Random Allocation; Rats; Rats, Inbred WKY; Reactive Oxygen Species

To report a case of myoclonus that developed after administration of dextromethorphan.. A 64-year-old man was diagnosed with chronic renal failure due to diabetic nephropathy. The patient started on peritoneal dialysis 6 months before he was hospitalized. Two days before hospitalization, he developed cough and sputum and he visited an outpatient clinic, where dextromethorphan was prescribed. After taking a total of 30 mg of dextromethorphan, the patient developed myoclonus, tremor, agitation, slurred speech, and diaphoresis, which continued after he stopped taking the prescribed medicine. He visited an emergency department and was hospitalized for examination and treatment of myoclonus.. As the patient's dialysis schedule was adequate, these symptoms were likely not due to uremia. The blood concentration of dextromethorphan (2.68 ng/mL) 60 hours after the 30-mg dose was higher than expected, and the blood concentration of dextrorphan, a metabolite, was lower than expected. We suspected that myoclonus was due to dextromethorphan-related symptoms induced by CYP2D6, which primarily metabolizes dextromethorphan. We analyzed the CYP2D6 gene for polymorphisms and identified CYP2D6 (*)1/(*)10. The patient had been taking metoprolol 40 mg/day for 2 years. The blood concentration of metoprolol 6 hours after administration was 13 ng/mL, which suggests that it was metabolized normally. Metoprolol has another metabolic pathway, via CYP2C19, and this may have led to its lack of accumulation. Moreover, metoprolol may have bound to active CYP2D6. Thus, affinity for CYP2D6, protein-binding rate, and lipid solubility may influence these drug interactions. Total scores for the Adverse Drug Reaction (ADR) probability scale and the Drug Interaction Probability Scale (DIPS) were 9 (highly probable) and 3 (possible), respectively.. Myoclonus and other symptoms in this patient may have been caused by a prolonged high concentration of dextromethorphan due to CYP2D6 polymorphisms and drug interactions.

Topics: Adrenergic beta-Antagonists; Antihypertensive Agents; Antitussive Agents; Cough; Cytochrome P-450 CYP2D6; Dextromethorphan; Diagnosis, Differential; Drug Interactions; Genotype; Humans; Hypertension; Kidney Failure, Chronic; Male; Metoprolol; Middle Aged; Myoclonus; Peritoneal Dialysis; Serotonin Syndrome

Topics: Acetaminophen; Chlorpheniramine; Common Cold; Dextromethorphan; Drug Combinations; Drug Interactions; Humans; Hypertension; Phenylpropanolamine

There is a new, potentially fatal disorder that is infrequently reported. The apparent rareness may be because of a lack of recognition of the syndrome or its predisposing factors. Fluoxetine (Prozac, Dista Products Co, Division of Eli Lilly Co, Indianapolis, IN), sertraline (Zoloft, Roerig Division, Pfizer Inc, New York, NY), and paroxetine (Paxil, SmithKline Beecham Pharmaceuticals, Philadelphia, PA) belong to a new class of antidepressant medication: the serotonin reuptake-inhibitors (SRIs). The relative safety profile of the SRIs has led to their widespread use. However, a syndrome of excessive serotonergic activity, the "serotonin syndrome" (SS), has recently been recognized. It is characterized by changes in mental status, hypertension, restlessness, myoclonus, hyperreflexia, diaphoresis, shivering, and tremor. A high index of suspicion is required to make the diagnosis in these acutely ill patients. The most common agents implicated in SS are the monoamine oxidase inhibitors in combination with L-tryptophan or fluoxetine. A case of a patient with significant peripheral vascular disease who developed SS while taking paroxetine and an over-the-counter cold medicine is reported. There have been no prior reports of this interaction. Discontinuation of the offending agents, sedation, and supportive care are the mainstays of treatment. The interactions of serotonin with platelets and vascular endothelium are also discussed.

Topics: Acetaminophen; Acute Disease; Akathisia, Drug-Induced; Blood Platelets; Dextromethorphan; Diagnosis, Differential; Doxylamine; Drug Combinations; Drug Interactions; Drug Therapy, Combination; Endothelium, Vascular; Ephedrine; Humans; Hypertension; Male; Middle Aged; Myoclonus; Nonprescription Drugs; Paroxetine; Peripheral Vascular Diseases; Promethazine; Pseudoephedrine; Sweating; Syndrome

Topics: Dextromethorphan; Drug Interactions; Drug Therapy, Combination; Ephedrine; Humans; Hypertension; Monoamine Oxidase Inhibitors; Nonprescription Drugs; Patient Education as Topic; Phenylephrine; Product Labeling